Leafcurl Ash Aphid, Woolly Apple Aphid and Woolly Beech Aphid
Prociphilus fraxinifolii; Eriosoma lanigerum; Phyllaphis fagi
Left: Woolly apple aphid colony (Whitney Cranshaw, Colorado State University, Bugwood.org); Right: Long-term damage to apple tree (H. J. Larsen, Bugwood.org)
- small, ~ 1/8 inch; pear shaped; color variable depending on species
- bodies covered in a white, waxy filament that gives a cottony or woolly appearance (more apparent on some species than others)
Host Plants, Diet & Damage
- cotoneaster, hawthorn, beech, ash, crabapple, firethorn, elm, etc.
- attack roots, trunks, limbs, leaves and shoots
- white, waxy substance can build up on plants
- some species curl, twist, or cup leaves or feed on roots
- honeydew or sooty mold may be present
Biology, Life Cycle & Damaging Life Stage
- some have alternate hosts; others migrate between different parts of the same plant
- overwinter as immatures on roots or as eggs on bark
- emerge in spring and move up trunks to feed on leaves
- mid-summer through fall, aphids migrate back to ash roots to overwinter
- when aphid populations become high, winged aphids will fly to nearby hosts
- winged adults may emerge from the roots in fall to mate
- These aphids have little negative effect on tree health; tolerate pest.
- Monitor bark, branches and undersides of leaves for aphids in the spring.
- Waxy coating and protection from curling leaves make cover sprays less effective.
- Apply a systemic insecticide (neonicitinoid) in the spring.